The objective of this project is to assess the prophylactic value of intravenous gamma globulin (IVGG) containing high RS Virus antibody titers in the prevention of complications associated with RS Virus infection in high risk infants and children, specifically those with bronchopulmonary dysplasia and congenital heart disease. The assessment will be made through the conduct of a phased clinical trial. Phase 1 of this trial will assure the safety of IVGG in this population of high risk children. Information on dosage, pharmacokinetics, and feasibility of study design will also be obtained. Following the completion of the Phase 1 objectives, a full-scale Phase 2 trial will be initiated. This controlled trial will assess the prophylactic efficacy of IVGG during three RS Virus seasons. Specific endpoints will include the ability of IVGG to prevent serious lower respiratory tract complications, including hospitalization, which are often observed in this population following RS Virus infection. In addition, active surveillance on type specific RS Virus activity will be conducted and compared in three geographically distinct regions. Follow-up studies of participants receiving IVGG will allow for additional information on the overall morbidity and mortality associated with this group, and the impact of re- infection.